Detecting apparatus and image forming apparatus

ABSTRACT

A detecting apparatus includes: a light emitting element which emits light toward a detection material; a light receiving element which receives reflected light from the detection material; and an apparatus main body having an opening/closing member which opens and closes an opening through which light emitted from the light emitting element and reflected light from the detection material pass through, the apparatus main body being capable of moving between a first position where the apparatus main body comes into contact with the detection material and a second position where the apparatus main body separates from the detection material, and the opening/closing member being configured to open when the apparatus main body moves to the first position and to close when the apparatus main body moves to the second position.

BACKGROUND OF THE INVENTION Field of the Invention

The present invention relates to a detecting apparatus irradiating lighttoward a detection material and detecting reflected light from thedetection material, and an image forming apparatus.

Description of the Related Art

In recent years, there is a growing need for higher image quality andbetter ecological measures in image forming apparatuses such as copiers,laser beam printers, and inkjet printers.

In situations where high image quality is required, conventionally, apatch image of a reference pattern formed on a recording material (adetection material) is detected by a detecting apparatus arranged insidean image forming apparatus. In addition, output data of the detectingapparatus is compared with data of the reference pattern to createcorrection data to be used for correcting image quality such as a tingeof an image to be formed next.

On the other hand, as an ecological measure, a detecting apparatusdetects an image representing surface properties of a recording material(a recording medium), and by determining a type of the recordingmaterial, image formation conditions are changed in accordance with thetype of the recording material so that printing is performed with theleast amount of energy.

Since the detecting apparatus used in these techniques read a patchimage on a recording material or an image representing surfaceproperties of the recording material, the detecting apparatus isdesirably arranged inside a transport path along which the recordingmaterial is transported during image formation.

However, arranging the detecting apparatus inside a transport pathcreates a risk of the detecting apparatus being contaminated by paperpowder or the like and losing the ability to accurately detect a patchimage on a recording material surface properties of the recordingmaterial.

As a solution to such a problem, a configuration is known in which ashutter (an opening/closing member) that opens and closes an opening ofa detecting apparatus is disposed (refer to Japanese Patent ApplicationLaid-open No. 2013-205258). An imaging portion is provided with anilluminating light source (a light emitting element) which emits lighttoward a reference chart (a detection material) through an opening and asensor (a light receiving element) which receives reflected light fromthe reference chart. By opening the shutter (the opening/closing member)during imaging and closing the shutter during normal transportation of arecording material during which imaging is not performed, contaminationby paper powder and the like is minimized.

In addition, in order to improve reading accuracy by the detectingapparatus, a distance between the light receiving element and therecording material is desirably controlled to be constant. Since aconstant distance can be realized by bringing the detecting apparatusinto close contact with the recording material during detection, amethod is conceivable in which the detecting apparatus is abuttedagainst an opposing surface that oppose the detecting apparatus in thetransport path to sandwich the recording material.

However, constantly abutting the detecting apparatus against theopposing surface of the transport path raises concerns that a defectiveimage may be created due to friction or the like and that a paper jam orthe like of recording material with low stiffness may occur. Therefore,the detecting apparatus is desirably brought into contact with theopposing surface of the transport path during reading and separated fromthe opposing surface when reading is not performed.

As a technique for realizing such a contacting/separating operation of adetecting apparatus, for example, Japanese Patent Application Laid-openNo. 2013-148503 proposes a configuration in which a colorimetric unit(an apparatus main body of a detecting apparatus) provided with acolorimetric sensor (a light receiving element) moves between a firstposition where the colorimetric unit presses a recording material (adetection material) and a second position where the pressing isreleased.

SUMMARY OF THE INVENTION

However, conventionally, a shutter and a configuration for causingcontact and separation of an apparatus main body of a detectingapparatus in order to improve detection accuracy of a recording materialand to maintain transportability of the recording material when readingis not performed only existed individually. In other words, a techniquethat provides both a shutter opening/closing function and acontact/separation function with respect to a detection material has notyet been disclosed.

An object of the present invention is to prevent contamination whileimproving detection accuracy of a detection material and maintainingtransportability when detection is not being performed by providing bothan opening/closing mechanism of an opening/closing member and acontact/separation mechanism with respect to the detection material.

In order to achieve the object described above, the present inventionincludes:

a light emitting element which emits light toward a detection material;

a light receiving element which receives reflected light from thedetection material; and

an apparatus main body having an opening/closing member which opens andcloses an opening through which light emitted from the light emittingelement and reflected light from the detection material pass through,wherein

the apparatus main body is capable of moving between a first positionwhere the apparatus main body comes into contact with the detectionmaterial and a second position where the apparatus main body separatesfrom the detection material, and

the opening/closing member opens in accordance with a movement of theapparatus main body to the first position and closes in accordance witha movement of the apparatus main body to the second position.

In addition, an image forming apparatus according to the presentinvention includes:

the detecting apparatus described above, wherein

the detecting apparatus is arranged opposite a transport path of arecording medium as the detection material.

According to the present invention, contamination can be prevented whileimproving detection accuracy of a detection material and maintainingtransportability when detection is not being performed by providing bothan opening/closing mechanism of an opening/closing member and acontact/separation mechanism with respect to the detection material.

Further features of the present invention will become apparent from thefollowing description of exemplary embodiments with reference to theattached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A and 1B are schematic perspective views showing an actuatingmechanism of a colorimetric unit according to a first embodiment of thepresent invention;

FIG. 2 is a schematic sectional view of an image forming apparatus towhich the present invention is applied;

FIG. 3 is a schematic view of a toner patch image formed on a recordingmaterial;

FIGS. 4A to 4C are an enlarged sectional view of a colorimetricapparatus and schematic views of an internal configuration of acolorimeter shown in FIGS. 1A and 1B;

FIGS. 5A to 5F are schematic views representing a relationship between acam gear and a slide cam shown in FIGS. 1A and 1B;

FIGS. 6A to 6F are schematic views representing a relationship betweenthe slide cam and a colorimetric unit shown in FIGS. 1A and 1B;

FIGS. 7A to 7E are schematic views representing a relationship betweenthe cam gear, the slide cam, and a shutter shown in FIGS. 1A and 1B;

FIG. 8 is a diagram showing a relationship between a phase of the camgear, a position of the colorimetric unit, and a degree of shutteropening shown in FIGS. 1A and 1B;

FIG. 9 is a diagram showing a relationship between a phase of the camgear shown in FIGS. 1A and 1B and a load torque of a motor;

FIGS. 10A and 10B are schematic perspective views showing an actuatingmechanism of a colorimetric unit according to a second embodiment of thepresent invention;

FIGS. 11A to 11E are schematic views representing a relationship betweena cam gear, a slide cam, and a shutter shown in FIGS. 10A and 10B;

FIG. 12 is a schematic sectional view of an image forming apparatusaccording to a third embodiment of the present invention;

FIGS. 13A and 13B are schematic perspective views showing an actuatingmechanism of a colorimetric unit according to the third embodiment ofthe present invention;

FIGS. 14A to 14E are schematic views representing a relationship betweena cam gear, a slide cam, and a shutter shown in FIGS. 13A and 13B;

FIGS. 15A to 15F are schematic views representing a relationship betweena cam gear and a slide cam according to a fourth embodiment of thepresent invention;

FIGS. 16A to 16F are schematic views representing a relationship betweenthe slide cam and a colorimetric unit according to the fourth embodimentof the present invention;

FIGS. 17A to 17E is a schematic view representing a relationship betweenthe cam gear, the slide cam, and a shutter according to the fourthembodiment of the present invention;

FIG. 18 is a diagram showing a relationship between a phase of the camgear, a position of the colorimetric unit, and a degree of shutteropening according to the fourth embodiment of the present invention;

FIG. 19 is a diagram showing a relationship between a phase of the camgear and a load torque of a motor according to the fourth embodiment ofthe present invention;

FIG. 20 is diagram showing, on a time axis, a relationship between anoutput of a colorimeter, a degree of shutter opening, and a position ofthe colorimetric unit according to the fourth embodiment of the presentinvention;

FIG. 21 is a block diagram of motor control according to the fourthembodiment of the present invention;

FIG. 22 is a flow chart for determining a contact/separation position ofthe colorimetric unit according to the fourth embodiment of the presentinvention;

FIGS. 23A and 23B are enlarged sectional views of a colorimetricapparatus according to a fifth embodiment of the present invention; and

FIGS. 24A and 24B are enlarged sectional views of colorimetricapparatuses according to other embodiments of the present invention.

DESCRIPTION OF THE EMBODIMENTS

Hereinafter, the present invention will be described in detail based onillustrated embodiments.

In the following description, an image forming apparatus mounted with acolorimetric apparatus as the detecting apparatus according to thepresent invention will be described as an example. Anelectrophotographic system color laser printer (hereinafter, LBP) isexemplified as the image forming apparatus. A colorimetric apparatusrefers to a device which, for the purpose of realizing a stable tinge ofan output image, detects the tinge of the output image and feeds backthe detected tinge to a process condition of the image formingapparatus. The detecting apparatus according to the present invention isnot limited to a colorimetric apparatus and can be utilized in aso-called media sensor or the like which photographs surface propertiesof a recording material (a recording medium) and determines a type ofthe recording material. In addition, while the present invention isapplied to an LBP as an image forming apparatus, the present inventionis not limited thereto and can also be applied to a copier, an inkjetprinter, and the like.

Configuration of Image Forming Apparatus

First, a schematic configuration of an LBP as an image forming apparatusto which the present invention is applied will be described withreference to FIG. 2. FIG. 2 shows a schematic sectional configuration ofthe LBP to which the present invention is applied.

First, an image forming portion will be described.

The image forming portion is provided with photosensitive members(hereinafter, referred to as photosensitive drums) 31Y, 31M, 31C, and31K for each station of the respective colors of YMCK. Charging rollers32Y, 32M, 32C, and 32K as primary charging portion, exposure scannerportions 33Y, 33M, 33C, and 33K, and developing devices 38Y, 38M, 38C,and 38K as developing portions are provided around the photosensitivedrums 31Y, 31M, 31C, and 31K.

The photosensitive drums 31Y, 31M, 31C, and 31K are configured byapplying an organic photoconductive layer on an outer circumference ofan aluminum cylinder, and rotate as a driving force of a drive motor(not shown) is transmitted thereto. The drive motor rotates thephotosensitive drums 31Y, 31M, 31C, and 31K in a clockwise direction inaccordance with an image forming operation.

The photosensitive drums 31Y, 31M, 31C, and 31K, the charging rollers32Y, 32M, 32C, and 32K, and the developing devices 38Y, 38M, 38C, and38K are integrally configured and constitute toner cartridges 39Y, 39M,39C, and 39K that are attachable to and detachable from an image formingapparatus main body.

The photosensitive drums 31Y, 31M, 31C, and 31K are arranged in a singlerow along an intermediate transfer belt 37, and primary transfer rollers34Y, 34M, 34C, and 34K are provided on the intermediate transfer belt 37so as to correspond to the respective photosensitive drums 31Y, 31M,31C, and 31K. The intermediate transfer belt is an endless belt which isstretched between a driver roller 41 and a tension roller 40 and whichis subjected to tension by an auxiliary roller 42. In addition, asecondary transfer roller 43 comes into contact with a section where theintermediate transfer belt 37 is wound around the driver roller 41 toconstitute a secondary transfer portion.

A paper feeding cassette 44 which stores a recording material P that isa recording medium is arranged below the intermediate transfer belt 37.In addition, a paper feeding transport path A is provided whichtransports the recording material P in the paper feeding cassette 44toward the secondary transfer portion that is a contact region of thesecondary transfer roller 43 and the intermediate transfer belt 37 usingpaper feeding rollers 45 and 46. Furthermore, a fixing portion 51 isarranged above the secondary transfer portion, and a paper dischargingtransport path B which discharges the recording material P having beendischarged from the fixing portion 51 to a paper discharge tray 52 on anupper surface of the apparatus using a paper discharge roller 50 isprovided above the fixing portion 51. In addition, in the presentembodiment, a duplex transport path D which returns the recordingmaterial P from the paper discharging transport path B to the paperfeeding transport path while circumventing the fixing portion 51 isprovided.

Moreover, reference numeral 55 denotes a main body control portion andreference numeral 56 denotes an image formation control portion forcontrolling operations of the components described above.

Next, an operation of the LBP will be described.

When the main body control portion 55 described above receives an imagesignal, the recording material P is fed out from the paper feedingcassette 44 by the paper feeding rollers 45 and 46. Subsequently, therecording material P is temporarily sandwiched between roller-likesynchronizing rotating members or, in other words, a transporting rollerpair (a resist roller pair) 47 for synchronizing an image formingoperation to be described later with the transportation of the recordingmaterial P, and the recording material P stops and stands by.

On the other hand, the image formation control portion 56 drives theexposure scanner portions 33Y, 33M, 33C, and 33K in accordance with thereceived image signal. In addition, surfaces of the photosensitive drums31Y, 31M, 31C, and 31K having been uniformly charged by the chargingrollers 32Y, 32M, 32C, and 32K are exposed and scanned to form anelectrostatic latent image.

The developing devices 38Y, 38M, 38C, and 38K are means for visualizingthe electrostatic latent image and develop yellow (Y), magenta (M), cyan(C), and black (K) for each station. The respective developing devices38Y, 38M, 38C, and 38K are provided with sleeves 35Y, 35M, 35C, and 35Kand a developing bias for visualizing the electrostatic latent image isapplied to the developing devices 38Y, 38M, 38C, and 38K. In thismanner, the electrostatic latent image formed on the surfaces of thephotosensitive drums 31Y, 31M, 31C, and 31K is developed by thedeveloping devices 38Y, 38M, 38C, and 38K as a monochromatic tonerimage.

The intermediate transfer belt 37 is in contact with the photosensitivedrums 31Y, 31M, 31C, and 31K and rotates in synchronization with therotation of the photosensitive drums 31Y, 31M, 31C, and 31K in acounterclockwise direction during color image formation. The developedmonochromatic toner images are sequentially transferred due to theaction of a primary transfer bias applied to the primary transfer roller34 and becomes a multicolor toner image on the intermediate transferbelt 37.

Subsequently, the multicolor toner image formed on the intermediatetransfer belt 37 is transported to a secondary transfer nip portionformed by the driver roller 41 and the secondary transfer roller 43. Atthe same time, the recording material P standing by in a state of beingsandwiched by the transporting roller pair 47 is transported to thesecondary transfer nip portion while being synchronized with themulticolor toner image on the intermediate transfer belt 37 due to theaction of the transporting roller pair 47. The multicolor toner image onthe intermediate transfer belt 37 is collectively transferred due to theaction of a secondary transfer bias applied to the secondary transferroller 43.

The fixing portion 51 melts and fixes the transferred multicolor tonerimage while transporting the recording material P and is provided with afixing roller 51 a for heating the recording material P and a pressureroller 51 b for pressing the recording material P against the fixingroller 51 a. The fixing roller 51 a and the pressure roller 51 b areformed in a hollow shape, and a heater 51 ah is built into the fixingroller.

The recording material P holding the multicolor toner image istransported by the fixing roller 51 a and the pressure roller 51 b and,at the same time, heat and pressure are applied to the recordingmaterial P to fix the toner onto a recording material surface.

The recording material P after the toner image is fixed is discharged tothe paper discharge tray 52 by the paper discharge roller 50 to end theimage forming operation. Alternatively, when image formation is to beperformed on a second side, the recording material P is returned to thepaper feeding transport path A via the duplex transport path D by aswitchback operation at the paper discharging transport path B, and therecording material P is once again temporarily sandwiched by thetransporting roller pair 47 (the resist roller pair) and stops andstands by. Subsequently, the series of image forming operationsdescribed above is performed and an image is formed on the second sideof the recording material P. The duplex transport path D is configuredto extend inclined diagonally downward from the paper dischargingtransport path B so as to circumvent the fixing portion 51, subsequentlyextend vertically downward, and further change directions in a U-shapeand merge with the paper feeding transport path A. A first transportingroller pair 61, a second transporting roller pair 62, and a thirdtransporting roller pair 63 are sequentially arranged at prescribedintervals on the duplex transport path D in a downward direction fromthe side of the paper discharging transport path B.

Cleaning means 48 is configured to clean toner remaining on theintermediate transfer belt 37 as untransferred toner, and theuntransferred toner collected by the cleaning means 48 is stored in acleaner container 49 as waste toner.

Colorimetry of Toner Patch

Next, colorimetry of a toner patch by a colorimetric apparatus 100 whichconstitutes the detecting apparatus according to the present inventionwill be described.

As shown in FIG. 2, the colorimetric apparatus 100 is provided in avertically extending region of the duplex transport path D or, in theillustrated example, between the second transporting roller pair 62 andthe third transporting roller pair 63. The colorimetric apparatus 100 isprovided with a colorimetric unit 10 as an apparatus main body whichperforms colorimetry of an image on the recording material P and outputsa result of the colorimetry as electronic data.

When a colorimetric mode of a toner patch T is started, first, the tonerpatch T that is a patch image for image quality correction such as thatshown in FIG. 3 is formed on the recording material P by the series ofoperations described earlier. The toner patch T is created by, for eachcolor, forming images of a plurality of basic patterns with differentdensities in a single row along a transport direction of the recordingmaterial P in a central section in a width direction that isperpendicular to the transport direction.

The recording material P having passed through the fixing portion 51 istransferred to the duplex transport path D due to a switchback operationat the paper discharging transport path B, and colorimetry of the tonerpatch T formed on the recording material P is sequentially performed bythe colorimetric unit 10 in synchronization with the transportation ofthe recording material P. In order to perform colorimetry of the tonerpatch T formed at the center in the width direction of the recordingmaterial P, the colorimetric unit 10 is arranged in a directionperpendicular to a transport direction Y (vertically downward in theillustrated example) of the duplex transport path D or, in other words,arranged opposite a central section of longitudinal directions of thesecond and third transporting roller pairs 62 and 63.

The recording material P after colorimetry by the colorimetric unit 10and having passed through the duplex transport path D makes a U-turn ata lower end of the duplex transport path D and returns to the paperfeeding transport path A, passes through the secondary transfer portionand the fixing portion 51, and is discharged to the paper discharge tray52 by the paper discharge roller 50.

The series of image forming operations and toner patch colorimetricoperations are controlled by the main body control portion 55, andcolorimetric data of the toner patch T measured by the colorimetric unit10 is sent to the main body control portion 55. At the main body controlportion 55, color correction data is created based on the colorimetricdata and fed back to image information of an image to be formed next.

First Embodiment

Next, a colorimetric apparatus (detecting apparatus) 100 according to afirst embodiment of the present invention will be described in detailwith reference to FIGS. 1 and 4 to 7.

Colorimetric Unit

First, a schematic configuration of the colorimetric unit 10constituting the colorimetric apparatus 100 will be described withreference to FIGS. 4A to 4C. FIG. 4A shows a separation state in whichthe colorimetric unit 10 is separated from a transport surface Da whichguides the recording material P, and FIG. 4B shows a contact state inwhich the colorimetric unit 10 is in contact with the transport surfaceDa. FIG. 4C is a schematic view of an internal configuration of thecolorimetric unit 10 shown in FIG. 4B as viewed from the direction Y.

The colorimetric unit 10 is arranged so as to face the duplex transportpath D and is movable forward and backward in a perpendicular directionwith respect to the transport surface Da of the duplex transport path Dwhich opposes the colorimetric unit 10. In the following description, acontact direction in which the colorimetric unit 10 comes into contactwith the transport surface Da will be denoted by X and the transportdirection of the recording material P will be denoted by Y. In addition,for each component, a surface on a side of the transport surface Da willbe referred to as a front surface and a surface on an opposite side ofthe transport surface Da will be referred to as a rear surface.

The colorimetric unit 10 includes a colorimeter 11 as a detectingportion which performs colorimetry of a toner patch on the recordingmaterial P (a detection material) passing through the duplex transportpath D and a shutter 14 as an opening/closing member which opens andcloses a colorimetric window 11 a that is an opening of the colorimeter11. The colorimetric unit 10 is also provided with a colorimeter base 13for fixing the colorimeter 11 and a colorimeter cover 12 as a covermember that covers the colorimeter 11 and the shutter 14. Thecolorimetric window 11 a is protected so that dust, paper powder, andthe like do not penetrate into the colorimeter 11 by having, forexample, an opening surface closed by glass, a cover sheet, or the like.The shutter 14 is a member for preventing the opening surfaceconstituted by glass, a cover sheet, or the like of the colorimetricwindow 11 a from being contaminated by dust, paper powder, and the like.

The colorimeter 11 includes a light source (a light emitting element)111 such as an LED which irradiates the toner patch on the recordingmaterial P (the detection material) with light and a light receivingelement 112 such as a line sensor which receives reflected light fromthe toner patch. The colorimetric window 11 a is a portion which lightemitted from the light source 111 and reflected light from the recordingmaterial P pass through and which is opened and closed by the shutter14.

As exemplified in FIG. 4C, an internal configuration of the colorimeter11 includes a diffraction grating 115 which disperses diffused andreflected light from the recording material P, and the colorimeter 11 isconfigured to receive light dispersed by the diffraction grating 115with the light receiving element 112. A light guiding member 113-1provided with a lens which converges irradiation light from the lightsource 111 onto the recording material is arranged in a recordingmaterial reflection optical path from the light source 111, and a lightguiding member 113-2 provided with a lens which converges reflectedlight onto the diffraction grating 115 and a slit 116 are arranged in anoptical path from the recording material to the diffraction grating 115.However, the internal configuration of the colorimeter 11 is not limitedto the illustrated configuration and need only be a configurationincluding dispersing means such as the diffraction grating 115 in theillustrated example, a prism, or the like. Various configurations can beadopted with respect to arrangements of the light source 111, the lightreceiving element 112, and the diffraction grating 115 andconfigurations of the optical paths depending on an arrangement space, aposition of the colorimetric window 11 a, and the like.

The colorimeter base 13 is a plate-like member which is fixed to a rearsurface of the colorimeter 11 and which is provided parallel to thetransport surface Da. An L-shaped engagement piece 130 which includes acontact region 13 a and which engages with a slide cam 15 such as thatshown in FIGS. 1A and 1B is provided on a rear surface of thecolorimeter base 13. The engagement piece 130 has a base section 13 bwhich extends in an opposite direction to a contact direction X from therear surface of the colorimeter base 13 and a bent section 13 c whichbends parallel to a transport direction Y from a tip of the base section13 b, and the contact region 13 a is provided so as to project from thebent section 13 c. The slide cam will be described later.

The colorimeter cover 12 has an open box-like sectional shape with aside of the colorimeter base 13 being open, and an end of thecolorimeter cover 12 is fixed to the colorimeter base 13 and constitutesa housing together with the colorimeter cover 12. In addition, a frontsurface 12 b opposite the duplex transport path D constitutes a planeparallel to the transport surface Da of the opposing duplex transportpath D. The opening 12 a is also provided on the front surface 12 b ofthe colorimeter cover 12. An opening surface of the opening 12 a is notclosed by glass, a cover sheet, or the like as was the case with thecolorimetric window 11 a. The opening 12 a is not closed by glass, acover sheet, or the like because the opening 12 a is a member whichcomes into contact with the transport surface Da and the presence ofglass, a cover sheet, or the like may cause a decline in detectionaccuracy due to the opening 12 a being damaged or dust, paper powder, orthe like adhering to the glass, the cover sheet, or the like by cominginto contact with the recording material P during detection. However,since dust, paper powder, or the like passes through the opening 12 a ifthe opening 12 a is hollow, a configuration is adopted which preventscontamination by covering the opening surface of the colorimetric window11 a with the shutter 14.

With the colorimetric unit 10, a position where the front surface 12 bof the colorimeter cover 12 facing the duplex transport path D is incontact with the transport surface Da is a contact position (the firstposition) (refer to FIG. 4B) and a position where the front surface 12 bis separated from the transport surface Da is a separation position (thesecond position) (FIG. 4A).

The colorimetric unit 10 is biased in the contact direction X withrespect to the transport surface Da by a biasing member 18 that is thefirst biasing member. The biasing member 18 is arranged so as to press arear surface of the colorimetric unit 10. In other words, in acompressed state, one end of the biasing member 18 engages with a rearsurface of the colorimeter base 13 and another end of the biasing member18 engages with a main body frame (not shown).

At the separation position, a gap between the front surface 12 b of thecolorimeter cover 12 and the transport surface Da is set more or lessequal to a gap of the duplex transport path D and functions as atransport surface which guides a recording surface side of the tonerpatch T of the colorimetric unit 10. An upstream-side portion of a frontsurface of the colorimetric unit 10 is provided with an inclined surfacewhich is inclined so that a gap with the transport surface Da graduallywidens toward an upstream end.

During colorimetry of the toner patch, at the contact position, thefront surface 12 b of the colorimeter cover 12 presses the recordingmaterial P against the transport surface Da due to a biasing force(which does not affect a toner image and which does not obstructtransportation) of the biasing member 18, and the recording material Pis sandwiched and transported by the colorimetric unit 10 and thetransport surface Da. This is done in order to transport the recordingmaterial P in a state where a variation in distance between therecording material P and the colorimeter 11 in the colorimetric unit 10is minimized. Accordingly, the toner patch T for colorimetry formed onthe recording material P can be read in a stable manner and a highcolorimetric accuracy of the toner patch T can be ensured.

In addition, a white reference plate 30 as the reference section isarranged on the transport surface Da which is an opposing sectionopposed by the colorimetric unit 10. The white reference plate 30provides a reference for toner patch colorimetry, and by performingcolorimetry of the white reference plate 30 prior to colorimetry of thetoner patch T on the recording material P, color reproducibility isensured.

In other words, before performing colorimetry of the toner patch T onthe recording material P, the front surface 12 b of the colorimetercover 12 of the colorimetric unit 10 is moved to the contact positionwith the transport surface Da and brought into close contact with thewhite reference plate 30 (refer to FIG. 4B). At this point, colorimetryof the white reference plate 30 is performed and a result of thecolorimetry is stored in main body control portion 55 as a referencecolor. Subsequently, as described earlier, colorimetry of the tonerpatch T on the recording material P is performed, color correction datais created by comparing the stored reference color information with acolorimetry result of the toner patch, and the color correction data isfed back to a process condition of image formation.

Configurations of Colorimetric Unit and Actuating Mechanism

Next, the colorimetric unit 10 which constitutes the colorimetricapparatus 100 and an actuating mechanism 22 which realizes anadvancing/retracting operation (a contacting/separating operation) ofthe colorimetric unit 10 with respect to the duplex transport path Dwill be described in detail with reference to FIGS. 1A and 1B.

FIGS. 1A and 1B are schematic perspective views showing the colorimetricunit 10 and an actuating mechanism thereof according to the presentfirst embodiment, in which FIG. 1A is a perspective view of thecolorimetric unit 10 as seen from a front surface side and FIG. 1B is avertically flipped perspective view of the colorimetric unit 10 shown inFIG. 1A as seen from a rear surface side.

Configurations of Shutter 14 and Colorimetric Window 11 a ofColorimetric Unit 10

As described above, the colorimetric unit 10 is constituted by thecolorimeter 11, the colorimeter base 13, the colorimeter cover 12, andthe shutter 14, and these components are movable in the contactdirection X and in a separation direction that is opposite to thecontact direction X in an integrated manner. Since the colorimeter base13 and the colorimeter cover 12 are as described with reference to FIGS.4A to 4C, the following description will mainly focus on the shutter 14and the colorimetric window 11 a provided in the colorimeter 11.

The shutter 14 is configured to, in conjunction with the colorimetricunit 10, open when the colorimetric unit 10 is at the contact position(the first position) and close when the colorimetric unit 10 is at theseparation position (the second position).

The colorimetric window 11 a is provided on a front surface of thecolorimeter 11, and colorimetry of the toner patch T on the recordingmaterial P on the transport surface Da or an image of the whitereference plate 30 on the transport surface Da is performed through thecolorimetric window 11 a. A opening 12 a corresponding to thecolorimetric window 11 a of the colorimeter 11 is also formed on thefront surface 12 b of the colorimeter cover 12.

The shutter 14 is constituted by a thin plate arranged along the frontsurface of the colorimeter 11, and the shutter 14 is configured so as toswing along the front surface of the colorimeter 11 via a spindle 14 band to open and close so as to cross the colorimetric window 11 a in adirection perpendicular to the contact direction X. The spindle 14 brotatably supports one end of the shutter 14 with respect to thecolorimeter base 13 and is configured so as swing between a closedposition at which a light shielding surface section 14 a of the shutter14 closes the colorimetric window 11 a and an open position at which thelight shielding surface section 14 a opens the colorimetric window 11 a.The spindle 14 b extends parallel to the contact direction X andprojects from a rear surface side of the colorimeter base 13, and alever 14 c for rotating the shutter 14 is mounted to a projected end ofthe spindle 14 b.

Configuration of Actuating Mechanism 22

The actuating mechanism 22 is provided with a motor 20 as a drivingsource, a worm 16 mounted to an output shaft of the motor 20, and a camgear 17 which meshes with the worm 16. The cam gear 17 is configuredsuch that a worm wheel 17 c which meshes with the worm 16 andconstitutes a worm gear and a rotating cam 170 are integrated by acommon rotating shaft 17 b, and the rotating cam 170 is rotated byrotation of the worm wheel 17 c. In addition, the slide cam 15 whichengages with the rotating cam 170 and which is linearly driven (linearreciprocating motion) by a prescribed distance by a rotating motion ofthe cam gear 17 is provided. A movement direction of the slide cam 15 isa direction perpendicular to the transport direction Y of the recordingmaterial P and also perpendicular to the contact direction X of thecolorimetric unit 10. In the movement direction of the slide cam 15, onemovement direction will be referred to as a forward movement direction Fand another movement direction will be referred to as a backwardmovement direction H.

The motor 20 is fixed to the main body frame (not shown), and the outputshaft of the motor 20 is oriented in a direction perpendicular to thetransport direction Y of the recording material of the slide cam 15 andalso perpendicular to an operating direction of the colorimetric unit10. With respect to a rotation of the motor 20, a direction of arotational axis of the cam gear 17 is converted by the worm 16 into adirection parallel to the contact direction X of the colorimetric unit10.

The slide cam 15 is supported so as to be movable in a slide direction(F, H) but not movable in the transport direction Y and the contactdirection X. The slide cam 15 is arranged at a prescribed interval in anopposite direction to the contact direction X on a rear surface side ofthe colorimeter base 13 of the colorimetric unit 10. The slide cam 15 isconfigured so as to include a cam main body section 150, a cam receivingsection 151 provided at one end in the slide direction (F, H) of the cammain body section 150, and a shutter pressing section 15 d provided atanother end in the slide direction of the cam main body section 150. Theshutter pressing section 15 d is provided so as to bend toward a tip ofan extension piece 15 d 1 that extends from the other end of the cammain body section 150, and the shutter pressing section engages thelever 14 c during a reciprocating movement of the slide cam 15 andpresses the shutter 14 in a direction in which the shutter 14 closes.

The cam main body section 150 is a frame body in which both ends of apair of upper and lower slide pieces 15 e and 15 e extending parallel toeach other in the slide direction across a prescribed interval areconnected to each other by vertical pieces, and the biasing member 18described earlier is arranged using a space between the slide pieces 15e and 15 e.

The cam receiving section 151 is constituted by a plate-shaped sectionperpendicular to the contact direction X and is provided with arectangular opening 152 into which the rotating cam 170 of the cam gear17 fits. The opening 152 has first and second cam receiving surfaces 15a and 15 b that are two inside surfaces which extend in a directionperpendicular to the slide direction and which oppose each other and twoinside surfaces 15 g 1 and 15 g 2 which extend in a direction parallelto the slide direction (F, H) and which oppose each other. Among the twoinside surfaces that extend in a direction perpendicular to the slidedirection, the first cam receiving surface 15 a is far from the cam mainbody section 150 and the second cam receiving surface 15 b is close tothe cam main body section 150.

The rotating cam 170 of the cam gear 17 is an egg-shaped plate cam fixedto the rotating shaft 17 b, and when a portion with a largest radius ofa cam surface is considered a top cam surface 17 a, a major axis of therotating cam 170 is equal to a distance between the first cam receivingsurface 15 a and the second cam receiving surface 15 b. On the otherhand, the two inside surfaces 15 g 1 and 15 g 2 which are parallel tothe slide direction are configured so that the top cam surface 17 a ofthe rotating cam 170 does not interfere with the inside surfaces 15 g 1and 15 g 2 while the rotating cam 170 is rotating, and a distancebetween the inside surfaces 15 g 1 and 15 g 2 is set to an interval thatprevents interference with the top cam surface 17 a. The slide cam 15reciprocates in the slide direction due to rotation of the cam gear 17.

The contact region 13 a of the engagement piece 130 which comes intocontact with the slide piece 15 e of the slide cam 15 reciprocates in aprescribed range between a forward movement limit and a backwardmovement limit of a rear surface of the slide piece 15 e in accordancewith a reciprocation of the slide cam 15. In this case, the forwardmovement direction F is a direction in which the cam main body section150 of the slide cam 15 separates from the rotating shaft 17 b of therotating cam 170, and the backward movement direction H is a directionin which the cam main body section 150 approaches the rotating shaft 17b of the rotating cam 170.

In a range of sliding movement of the contact region 13 a, the rearsurface of the slide piece 15 e constitutes an inclined surface 15 cwhich is gradually inclined in a direction approaching a transportsurface from the backward movement limit toward the forward movementlimit. In other words, the rear surface of the slide piece 15 e isprovided with a difference in level including a first surface 15 e 1which is far from the transport surface Da and a second surface 15 e 2which is close to the transport surface Da, the first surface 15 e 1 andthe second surface 15 e 2 separated from each other by the inclinedsurface 15 c. In addition, a click section 15 f is formed at a boundarysection between the inclined surface 15 c and the first surface 15 e 1which is far from the transport surface Da so as to project from theboundary section.

FIGS. 1A and 1B show a state where the contact region 13 a is at aforward movement limit position or, in other words, the contact region13 a is positioned near a boundary section between the inclined surface15 c and the second surface 15 e 2 which is close to the transportsurface Da, and holds the colorimetric unit 10 at a contact position.

The top cam surface 17 a of the cam gear 17 is positioned on the secondcam receiving surface 15 b, and when the slide cam 15 is positioned atthe forward movement limit (the colorimetric unit 10 is at the contactposition), the shutter pressing section 15 d does not engage with thelever 14 c and the shutter 14 is at the open position in a free state.When the slide cam 15 reaches the backward movement limit (thecolorimetric unit 10 is at the separation position), the shutterpressing section 15 d engages with the lever 14 c and moves the shutter14 to the closed position.

Description of Contacting/Separating Operation of Colorimetric Unit 10

Next, a contacting/separating operation of the colorimetric unit 10 willbe described with reference to FIGS. 5 and 6.

FIGS. 5A to 5F are schematic views representing a relationship betweenthe cam gear 17 and the slide cam 15 shown in FIGS. 1A and 1B, and FIGS.6A to 6F are schematic views representing a relationship between theslide cam 15 and the colorimetric unit 10 and showing the slide cam 15from below. In FIGS. 6A to 6F, while detection materials differ betweena case where colorimetry of the toner patch T on the recording materialP is performed and a case where colorimetry of the white reference plate30 of the transport surface Da is performed and contact positions differbetween the cases by a thickness of the recording material P, therecording material P and the white reference plate 30 collectivelyconstitute a colorimetric surface Z of the detection material. In somecases where the white reference plate 30 is not provided, the transportsurface Da itself may be the detection material.

Transition Operation from Separation Position to Contact Position

First, an operation when the colorimetric unit 10 makes a transitionfrom the separation position to the contact position with respect to thecolorimetric surface Z will be described.

Normally, the colorimetric unit 10 is at the separation position wherethe colorimetric unit 10 is retracted from the colorimetric surface Z(FIG. 6A). At this point, as shown in FIG. 5A, the top cam surface 17 aof the rotating cam 170 is in perpendicular contact with the first camreceiving surface 15 a of the cam receiving section 151 of the slide cam15. Let us assume that a phase of the cam gear 17 at this point is 0degrees (a first dead center). At this point, the slide cam 15 ispositioned at the backward movement limit in a backward movementdirection H. The backward movement direction H is a direction in whichthe cam main body section 150 of the slide cam 15 moves toward a side ofthe rotating shaft 17 b of the cam gear. The contact region 13 a of theengagement piece 130 of the colorimetric unit 10 which comes intocontact with the slide piece 15 e is at a position which is on the firstsurface 15 e 1 that is far from the colorimetric surface Z and which isnear a boundary section with the inclined surface 15 c, and engages withthe click section 15 f which is projected to the boundary section (referto FIG. 6A).

When the motor 20 is driven from this separation position, a rotationaldriving force of the motor 20 is transmitted to the cam gear 17 throughthe worm 16 and the cam gear 17 rotates in a direction E (in FIGS. 5A to5F, a counter-clockwise direction). When the cam gear 17 rotatesapproximately 90 degrees, as shown in FIG. 5B, the cam gear 17 starts tocome into contact with the second cam receiving surface 15 b of theslide cam 15. During a transition period (between FIGS. 5(a) and 5(b))of the cam gear 17 from 0 degrees to a contact start position with thesecond cam receiving surface 15 b, the slide cam 15 does not move andthe colorimetric unit 10 remains at a separation position where thecolorimetric unit 10 is separated from the colorimetric surface Z.

In other words, there is an idle period in which drive is nottransmitted from the rotating cam 170 to the slide cam 15 after thecolorimetric unit 10 reaches the separation position (the secondposition).

During this period, as shown in FIG. 6A, the colorimetric unit 10 isconfigured so as to be biased in the contact direction X by a biasingmember (not shown) and prevented from moving in a left-right directionin FIGS. 6A to 6F by a guide section (not shown).

When the cam gear 17 rotates further, the top cam surface 17 a of therotating cam 170 starts pressing the second cam receiving surface 15 bof the cam receiving section (a period from FIG. 5B to 5(c)), and theslide cam 15 starts to move in a forward movement direction F. Theforward movement direction F is a direction in which the cam main bodysection 150 of the slide cam 15 moves in a direction of separation fromthe rotating shaft of the cam gear 17.

When a driving force from the cam gear 17 starts to be transmitted tothe slide cam 15, as shown in FIG. 6C, the contact region 13 a mountsthe click section 15 f at the boundary between the first surface 15 e 1of the slide piece 15 e and the inclined surface 15 c. Accordingly, thecolorimetric unit 10 is pushed upward in an opposite direction to thecontact direction X. The click section 15 f is provided for the purposeof holding the colorimetric unit 10 at the separation position and actsto restrict movement of the slide cam 15 when the slide cam 15 starts tomove due to external force instead of due to being driven by the camgear 17. In other words, in order to move the slide cam 15, the contactregion 13 a of the engagement piece 130 provided in the colorimeter base13 must clear the click section 15 f against a biasing force of thebiasing member 18, and the colorimetric unit 10 is held at theseparation position using the resistance force.

When the click section 15 f passes the contact region 13 a of theengagement piece 130 of the colorimetric unit 10, as shown in FIG. 6B,the contact region 13 a of the colorimeter base 13 moves from the firstsurface 15 e 1 to the inclined surface 15 c. In addition, due to thebiasing force of the biasing member 18, a component force is generatedwith which the contact region 13 a presses the inclined surface 15 c inthe forward movement direction F. Accordingly, the slide cam 15 isreleased from the driving force of the cam gear 17, and a relationshipbetween the slide cam 15 and the cam gear 17 changes to a state wherethe top cam surface 17 a of the rotating cam 170 is separated from thesecond cam receiving surface 15 b as shown in FIG. 5C. At this point,with respect to the slide cam 15 and the colorimetric unit 10, the frontsurface 12 b of the colorimetric unit 10 comes into contact with thecolorimetric surface Z as shown in FIG. 6D. At this contact position Xl,the contact region 13 a is separated from the first surface 15 e 1 thatis closer to the transport surface of the slide cam 15, and thecolorimetric unit 10 comes into contact with the colorimetric surface Zin a stable manner. Meanwhile, as the cam gear 17 rotates further and arotational phase reaches 180 degrees, the top cam surface 17 a of therotating cam 170 comes into perpendicular contact with the second camreceiving surface 15 b and the slide cam 15 reaches the forward movementlimit in the forward movement direction (FIG. 5D).

At this point, a contact state of the colorimetric unit 10 is detectedby a photosensor 19 shown in FIGS. 5A to 5F. There is a timing at whicha light shielding section 15 h of the slide cam 15 shields thephotosensor 19 from light during a transition from the separationposition shown in FIG. 5A to the contact position shown in FIG. 5D, anda position where the cam gear 17 has been rotated by a certain phasefrom the timing is determined as a contact state. A detailed descriptionwill be given later.

Description of Operation from Contact Position to Separation Position

First, an operation when the colorimetric unit 10 makes a transitionfrom the contact position to the separation position will be described.

When making a transition to the separation position after colorimetry orthe like is completed, the motor 20 is rotationally driven. Even in thiscase, rotation occurs in the same direction E as when a transition ismade from the separation position to the contact position. In otherwords, the drivingly connected cam gear 17 rotates in the direction Eshown in FIGS. 5A to 5F. In the present embodiment, by constantlyrotating the motor 20 in one direction (the direction E) instead ofdriving the motor 20 in reverse, a circuit configuration for motorcontrol is simplified and cost reduction is achieved. In other words,only rotational drive in one direction is imparted to the rotating cam170 from the motor 20.

When the cam gear 17 rotates and reaches a state shown in FIG. 5E, thetop cam surface 17 a of the rotating cam 170 starts to come into contactwith the first cam receiving surface 15 a of the slide cam 15.Subsequently, the cam gear 17 reaches a state shown in FIG. 5F (thefirst dead center). The state at this point is equivalent to that shownin FIG. 5A.

Meanwhile, the slide cam 15 does not move during a period of transitionfrom FIG. 5D to FIG. 5E or, in other words, until a rotational phaseexceeds 270 degrees by a prescribed amount from 180 degrees and the camgear 17 comes into contact with the first cam receiving surface 15 a.Therefore, there is an idle period in which drive is not transmittedfrom the rotating cam 170 to the slide cam 15 after the colorimetricunit 10 reaches the contact position (the first position).

At this point, the colorimetric unit 10 is biased in the contactdirection X shown in FIGS. 5A to 5F by the biasing member 18 and thebiasing force creates a state where the front surface 12 b of thecolorimeter cover 12 is in contact with the colorimetric surface Z. Inthis case, the colorimetric surface Z changes depending on whether therecording material P is present or absent. In other words, thecolorimetric surface Z is a surface of the recording material P when anobject of colorimetry is the recording material P but the colorimetricsurface Z is a surface of the white reference plate 30 when therecording material P is not present.

When the cam gear 17 rotates and the top cam surface 17 a of therotating cam 170 presses the first cam receiving surface 15 a of theslide cam 15 during a period from FIG. 5E to 5(f), the slide cam 15starts to slidingly move in the backward movement direction H which isopposite to the forward movement direction F.

When drive from the cam gear 17 starts to be transmitted to the slidecam 15, the inclined surface 15 c of the slide cam 15 shown in FIG. 6Epresses the contact region 13 a of the engagement piece 130 of thecolorimetric unit 10 and pushes up the colorimetric unit 10 in anopposite direction (the separation direction) to the contact directionX. Due to the biasing force of the biasing member 18, a component forcewith which the contact region 13 a of the colorimeter base 13 pressesthe inclined surface 15 c in the forward movement direction F isgenerated on the contact region 13 a. Since the component forceconstitutes resistance to the cam gear 17, the cam gear 17 moves theslide cam 15 in the backward movement direction H against a resistanceforce that acts in the forward movement direction F. In other words, theslide cam 15 moves while being controlled by the top cam surface 17 a ofthe rotating cam 170. Subsequently, when the cam gear 17 rotates and thecontact region 13 a of the engagement piece 130 clears the click section15 f of the slide cam 15, the colorimetric unit 10 reaches a separationposition shown in FIG. 6F (FIG. 6A).

As described above, the biasing member 18 which biases the colorimetricunit 10 in the contact direction, the motor 20, the cam gear 17, and theslide cam 15 constitute a unit drive portion (an apparatus main bodydrive portion) according to the present invention. Among thesecomponents, the cam gear 17 and the slide cam 15 constitute the cammechanism which causes the colorimetric unit 10 to reciprocate betweenthe contact position (the first position) and the separation position(the second position). In addition, when the colorimetric unit 10 is atthe contact position (the first position), the colorimetric unit 10 ispressed against the recording material P by the biasing member 18.Furthermore, when the colorimetric unit 10 is at the separation position(the second position), the colorimetric unit 10 is held at theseparation position against the pressing force of the biasing member 18by the slide cam 15 and the rotating cam 170 of the cam gear 17 whichconstitute the cam mechanism.

Description of Operation of Shutter

Next, an operation of the shutter 14 of the colorimetric unit 10 will bedescribed with reference to FIGS. 7A to 7E. FIGS. 7A to 7E are diagramswhich show phases of the cam gear 17 and the slide cam 15 and anoperation of the shutter 14 and which is viewed from a surface on a sideof the colorimetric window in FIG. 1A in a similar manner to FIGS. 5A to5F.

Shutter 14 when Colorimetric Unit 10 Makes Transition from SeparationPosition to Contact Position

When the colorimetric unit 10 is at the separation position, as shown inFIG. 7A, the light shielding surface section 14 a of the shutter 14 isarranged so as to close the colorimetric window 11 a of the colorimeter11 which is a reading section of the colorimetric unit 10. The state atthis point will be referred to as a shutter closed state. The shutter 14is rotatably held by the colorimeter base 13 around a center of rotationof the spindle 14 b, and a biasing force due to the shutter's own weightis applied in a direction indicated by an arrow to a center of gravity Gof the shutter 14. In the state shown in FIG. 7A, a rotating force ofthe shutter 14 created by its own weight is held due to the lever 14 cfixed to the spindle 14 b of the shutter 14 coming into contact with theshutter pressing section 15 d of the slide cam 15.

Subsequently, as the slide cam 15 moves in the forward movementdirection F in accordance with a rotation of the cam gear 17, thecolorimetric window 11 a is gradually exposed and changes to a stateshown in FIG. 7B before reaching a state shown in FIG. 7C. When thestate shown in FIG. 7C is reached, the shutter 14 is held as a receivingsurface 14 d comes into contact with an abutted section (not shown) andthe colorimetric window 11 a enters a fully open state in which thecolorimetric window 11 a is completely exposed. This fully open statewill be referred to as a shutter open state. In other words, when thecolorimetric unit 10 is in a contact state, the shutter open stateexists.

As described above, the motor 20, the cam gear 17, the slide cam 15, andthe shutter pressing section 15 d provided in the slide cam 15constitute the shutter drive portion (the opening/closing member driveportion) according to the present invention. In other words, the shutterdrive portion and the unit drive portion are driven by the motor 20 thatis the same driving source.

In addition, the shutter 14 is biased in an opening direction by its ownweight, and the shutter drive portion is configured to perform drivingonly in an opposite direction to the biasing direction of the shutter 14or, in this example, only in a closing direction. Alternatively, theshutter 14 may be biased in the closing direction by its own weight andthe shutter drive portion may be configured to perform driving only inthe opening direction.

Shutter 14 when Colorimetric Unit 10 Makes Transition from ContactPosition to Separation Position

Next, an operation of the shutter 14 when the colorimetric unit 10 makesa transition from the contact position to the separation position willbe described with reference to FIGS. 7A to 7E.

When the colorimetric unit 10 is at the contact position, as shown inFIG. 7C, the shutter open state exists in which the light shieldingsurface section 14 a of the shutter 14 has completely opened thecolorimetric window 11 a of the colorimeter 11 that is the readingsection of the colorimetric unit 10. In the state shown in FIG. 7C, therotating force of the shutter 14 created by its own weight is held dueto the receiving surface 14 d coming into contact with the abuttedsection (not shown). Subsequently, as the slide cam 15 moves in thedirection H in accordance with a rotation of the cam gear 17, thecolorimetric window 11 a is gradually closed and changes to a stateshown in FIG. 7D before reaching a state shown in FIG. 7E (FIG. 7A).

At this point, the colorimetric unit 10 is in a separation state, andthe shutter closed state exists in which the light shielding surfacesection 14 a of the shutter 14 has completely closed the colorimetricwindow 11 a of the colorimeter 11 that is the reading section of thecolorimetric unit 10. A degree of opening of the colorimetric window 11a by the light shielding surface section 14 a of the shutter 14including the shutter open state and the shutter closed state describedabove will be defined as a degree of shutter opening.

FIG. 8 collectively shows a relationship among a rotational phase of thecam gear 17, a position of the colorimetric unit 10, and the degree ofshutter opening described above. In the diagram, an abscissa indicates aphase of the cam gear 17 and an ordinate indicates a position of thecolorimetric unit 10 and the degree of shutter opening.

Means for detecting a contact position and a separation position of thecolorimetric unit 10 will now be described.

As described earlier, the slide cam 15 moves in the direction F when thecolorimetric unit 10 makes a transition from the separation position inFIG. 5A to the contact position in FIG. 5C, and an output of W isobtained from the sensor 19 as shown in FIG. 8 at a timing where thelight shielding section 15 h shields the sensor 19. In the presentembodiment, at a timing where the cam gear 17 has rotated by aprescribed phase αdeg from the timing where the sensor 19 is shielded, adetermination is made that the colorimetric unit 10 has moved to thecontact position and the shutter 14 has changed to an open state. Theprescribed phase αdeg is set to an angle in a range of θ1deg at whichthe colorimetric unit 10 is at the contact position and in a range ofθ3deg at which the shutter 14 is in the open state.

Next, the slide cam 15 moves in the backward movement direction H duringa transition from the contact position in FIG. 5D to the separationposition in FIG. 5F, and an output of V is obtained from the sensor 19as shown in FIG. 8 at a timing where the light shielding section 15 hseparates from the sensor 19.

At a timing where the cam gear 17 has rotated by a prescribed phase βdegfrom the timing where the sensor becomes transmissive, a determinationis made that the colorimetric unit 10 has moved to the separationposition and the shutter 14 has changed to a closed state. Theprescribed phase βdeg is set to an angle in a range of θ2deg at whichthe colorimetric unit 10 is at the separation position and in a range ofθ4deg at which the shutter 14 is in the closed state.

As described above, phases of the cam gear 17 when the colorimetric unit10 is at the contact position and the separation position respectivelyexist with widths of θ1 and θ2. In addition, phases of the cam gear 17in the shutter open state and the shutter closed state also respectivelyexist with widths of θ3 and θ4. Accordingly, stop positions (αdeg fromthe sensor output W and βdeg from the sensor output V) of the motor 20which is the driving source that performs a contacting/separatingoperation of the colorimetric unit 10 and an opening/closing operationof the shutter 14 can be roughly set and control can be simplified.

In the present embodiment, a DC brush motor is used as the motor 20. DCbrush motors are inexpensive but rotational speeds thereofcharacteristically vary according to load torque. In other words, thelighter the load torque, the faster the rotation, and the heavier theload torque, the slower the rotation.

FIG. 9 is a diagram showing a relationship between a phase of the camgear 17 and a load torque applied to the motor 20 according to thepresent embodiment. An abscissa indicates a phase of the cam gear 17 andan ordinate indicates a load torque of the motor 20.

As shown in FIG. 9, a manner in which load torque varies differs betweena transition of the colorimetric unit 10 from the separation position tothe contact position and a transition from the contact position to theseparation position. This means that more time is required by the camgear 17 to rotate from 180 degrees to 360 degrees than to rotate by 180degrees from 0 degrees which is the state shown in FIG. 5A.

In other words, the time required for a transition from the separationposition to the contact position differs from the time required for atransition from the contact position to the separation position.Therefore, even if the torque applied to the motor varies throughrepetitive contacting/separating operations, as described above, leewayis given to the phase of the cam gear 17 when the colorimetric unit 10is at the contact position and the separation position and when theshutter 14 is in the open state and the closed state. As a result, avariation in a rotation time of the cam gear 17 due to the torquevariation can be absorbed and the colorimetric unit 10 and the shutter14 can be stopped at prescribed positions.

As described above, according to the present embodiment, by providingboth an opening/closing mechanism of the shutter 14 which protects thecolorimeter 11 of the colorimetric unit 10 and a contact/separationmechanism of the colorimetric unit 10 with respect to the recordingmaterial P, contamination of a reading section can be prevented whileimproving detection accuracy of the recording material P and maintainingtransportability when reading is not being performed.

In addition, since an opening/closing operation of the shutter 14 andthe contacting/separating operation of the colorimetric unit 10 can beperformed in an interlocked manner by one motor 20 (an actuator),control of a contact/separation state of the colorimetric unit 10 andcontrol of an open/closed state of the shutter 14 can be performed usingthe same components and operation timings of the colorimetric unit 10and the shutter 14 can be controlled with accuracy. Furthermore,consolidating actuators into one motor 20 is also advantageous in termsof saving space.

Second Embodiment

Next, a second embodiment of the present invention will be describedwith reference to FIGS. 10 and 11. In the present embodiment, sincebasic configurations of an image forming apparatus to which the presentinvention is applied and a colorimetric unit provided in the imageforming apparatus are the same as those of the first embodiment, same orcorresponding functions to the first embodiment and elements sharing thesame configuration as those of the first embodiment will be assignedsame reference characters and a detailed description will be omitted.

FIGS. 10(a) and 10(b) are configuration diagrams of the colorimetricunit, and FIGS. 11(a) to 11(e) are explanatory diagrams of operations ofa cam gear, a slide cam, and a shutter, in which thecontacting/separating operation of the colorimetric unit and theopening/closing operation of the shutter according to the firstembodiment are driven by two actuators, namely, motors 20 and 200.

As shown in FIGS. 10A and 10B, the contacting/separating operation ofthe colorimetric unit 10 is performed via the worm 16, the cam gear 17,and the slide cam 15 using the motor 20 in a similar manner to the firstembodiment. Meanwhile, the shutter 14 is configured to be opened andclosed using the motor 200, via a worm 161 mounted on an output shaft ofthe motor 200 and a cam gear 171 which rotates by meshing with the worm161, and due to driving by the cam gear 171. The cam gear 171 isconfigured such that a worm wheel 171 c which meshes with the worm 161and constitutes a worm gear and a rotating cam 1710 are integrated by acommon rotating shaft 17 b, and the rotating cam 1710 is rotated byrotation of the worm wheel 17 c.

In other words, the movement of the colorimetric unit 10 and theopening/closing operation of the shutter 14 are made independent, and ashutter drive portion and a unit drive portion are respectively drivenby the motors 20 and 200 that are different driving sources.

Description of Operation from Shutter Closed State to Open State (FIGS.11(a) to 11(c))

First, a movement of the shutter 14 when the colorimetric unit 10 makesa transition from the separation position to the contact position willbe described.

FIGS. 11A to 11E are diagrams showing phases of the cam gear 171 and theslide cam 15 and a movement of the shutter 14. When the colorimetricunit 10 is at the separation position, as shown in FIG. 11A, the shutter14 is arranged so as to close the colorimetric window 11 a that is thereading section of the colorimetric unit 10. At this point, the shutter14 is held in a closed state by bringing a cam surface 171 a of the camgear 171 into contact with the lever 14 c. Subsequently, a driving forceis transmitted from the motor 200 to the cam gear 171 and, as the camgear 171 rotates in the direction E, a contact state between a top camsurface 171 a of the cam gear 171 and the lever 14 c is transformed. Dueto the transformation, the shutter 14 rotates in a direction I by itsown weight, the colorimetric window 11 a is gradually exposed, and theshutter 14 changes to a state shown in FIG. 11B before reaching a stateshown in FIG. 11C.

When the state shown in FIG. 11C is reached, the lever 14 c of theshutter 14 and the top cam surface 171 a of the cam gear 171 are in acompletely separated state, and the colorimetric window 11 a enters afully-open state in which the colorimetric window 11 a is completelyexposed as the receiving surface 14 d comes into contact with an abuttedsection (not shown). This fully open state will be referred to as ashutter open state. In other words, when the colorimetric unit 10 is ina contact state, the shutter open state exists.

Description of Operation from Shutter Open State to Closed State (FIGS.11(c) to 11(e))

Next, a movement of the shutter 14 when the colorimetric unit 10 makes atransition from the contact position to the separation position will bedescribed.

When the colorimetric unit 10 is at the contact position, as shown inFIG. 11C, the shutter open state exists in which the shutter 14 hascompletely opened the colorimetric window 11 a of the colorimetric unit10. In the state shown in FIG. 11C, the shutter 14 is held by having thereceiving surface 14 d come into contact with the abutted section (notshown) due to a rotating force created by the shutter's own weight.Subsequently, in accordance with the rotation of the cam gear 171 in thedirection E, the cam surface 171 a of the cam gear 171 starts to comeinto contact with the lever 14 c of the shutter 14 and rotates theshutter 14 in a direction Q. The colorimetric window 11 a is graduallyclosed and changes to a state shown in FIG. 11D before reaching a stateshown in FIG. 11E (FIG. 11A). At this point, the colorimetric unit 10 isin a separation state, and the shutter 14 is in a shutter closed statein which the colorimetric window 11 a of the colorimeter 11 of thecolorimetric unit 10 is completely closed by the shutter 14.

In this manner, both the opening/closing mechanism of the shutter 14which protects the colorimeter 11 of the colorimetric unit 10 and thecontact/separation mechanism of the colorimetric unit 10 with respect tothe recording material are provided, and the respective mechanisms aredriven by the two motors 20 and 200. In addition, by interlocking drivetimings, contamination of the colorimeter 11 can be prevented whileimproving detection accuracy of the recording material P and maintainingtransportability when reading is not being performed.

Furthermore, while motors are used as actuators in the presentembodiment, the use of motors is not restrictive and other actuatorssuch as solenoids, clutches, and the like may be used.

Third Embodiment

Next, a third embodiment of the present invention will be described withreference to FIGS. 12 to 14. Even in the present embodiment, since basicconfigurations of an image forming apparatus to which the presentinvention is applied and a colorimetric unit provided in the imageforming apparatus are the same as those of the first embodiment, same orcorresponding functions to the first embodiment and elements sharing thesame configuration as those of the first embodiment will be assignedsame reference characters and a detailed description will be omitted.

FIG. 12 is a sectional view of an image forming apparatus according tothe third embodiment of the present invention, FIGS. 13(a) and 13(b) areconfiguration diagrams of a colorimetric unit, and FIGS. 14(a) to 14(e)are explanatory diagrams of operations of a cam gear, a slide cam, and ashutter. An arrangement of the colorimetric unit relative to thetransport path and an opening/closing configuration of the shutter havebeen changed from the first embodiment.

As shown in FIG. 12, the present embodiment adopts a configuration inwhich the colorimetric unit 10 is provided at a location where theduplex transport path D is horizontal and the recording material P istransported below the colorimetric unit 10. In addition, as shown inFIGS. 13(a) and 13(b), an opening/closing operation of the shutter 14 iscontrolled by a shutter biasing member 21 which is the second biasingmember that biases the shutter 14 and by the slide cam 15.

Description of Operation from Shutter Closed State to Open State (FIGS.14(a) to 11(c))

First, a movement of the shutter 14 when the colorimetric unit 10 makesa transition from the separation position to the contact position willbe described. FIGS. 14A to 14E are diagrams showing phases of the camgear 17 and the slide cam 15 and a movement of the shutter 14.

When the colorimetric unit 10 is at the separation position, as shown inFIG. 14A, the shutter 14 is arranged so as to close the colorimetricwindow 11 a that is the reading section of the colorimetric unit 10. Theshutter 14 is held so as to be rotatable around the spindle 14 b, andthe lever 14 c is subjected to a biasing force in a direction of anarrow I from the shutter biasing member 21. In the state shown in FIG.14A, a rotating force due to the biasing force from the shutter biasingmember 21 is held due to the lever 14 c of the shutter 14 coming intocontact with the shutter pressing section 15 d of the slide cam 15.

Subsequently, as the cam gear 17 rotates, the slide cam 15 moves in thedirection F and the shutter 14 receives a force from the shutter biasingmember 21 and rotates in the direction I. Due to the rotation, thecolorimetric window 11 a is gradually exposed and the shutter 14 changesto a state shown in FIG. 14B before reaching a state shown in FIG. 14C.

When the state shown in FIG. 14C is reached, as the receiving surface 14d of the shutter 14 comes into contact with an abutted section (notshown), the colorimetric window 11 a enters a fully-open state in whichthe colorimetric window 11 a is completely exposed. This fully openstate will be referred to as a shutter open state. In other words, whenthe colorimetric unit 10 is in a contact state, the shutter open stateexists.

Description of Operation from Shutter Open State to Closed State (FIGS.14(c) to 14(e))

Next, a movement of the shutter 14 when the colorimetric unit 10 makes atransition from the contact position to the separation position will bedescribed.

When the colorimetric unit 10 is at the contact position, as shown inFIG. 14C, the shutter open state exists in which the shutter 14 hascompletely opened the colorimetric window 11 a of the colorimetric unit10. In the state shown in FIG. 14C, the shutter 14 is held due to therotating force created by the biasing force from the shutter biasingmember 21 causing the receiving surface 14 d to come into contact withthe abutted section (not shown). Subsequently, as the cam gear 17rotates, the slide cam 15 moves in the direction H and the shutter 14receives a force from the shutter pressing section 15 d of the slide cam15 and rotates in the direction Q. Due to the rotation of the shutter14, the colorimetric window 11 a is gradually closed and changes to astate shown in FIG. 14D before reaching a state shown in FIG. 14E (FIG.14A). At this point, the colorimetric unit 10 is in a separation state,and the shutter closed state exists in which the shutter 14 hascompletely closed the colorimetric window 11 a that is the readingsection of the colorimetric unit 10.

In this manner, by restricting an operation of the shutter 14 accordingto the third embodiment by the slide cam 15 and the shutter biasingmember 21, the colorimetric unit 10 can be controlled without beingaffected by an installation direction of the colorimetric unit 10 andsimilar effects to the first embodiment can be obtained.

As described above, while an interlocked operation of the colorimetricunit and the shutter has been described using a slide cam in the firstto third embodiments, the present invention is not limited thereto andmay be applied to, for example, operations using a rotating cam. Inaddition, biasing means, biasing directions, and the like in an openingdirection of the shutter as described in the embodiments simplyrepresent examples and any configuration may be adopted as long asrequirements of the present invention are satisfied.

Moreover, while a colorimetric unit that performs colorimetry of a colorpatch image has been described as an example of a colorimetric apparatusin the respective embodiments presented above, a colorimetric unit thatperforms colorimetry of a black and white patch image may be usedinstead. In addition, the detecting apparatus may be used in a so-calledmedia sensor that is an imaging apparatus which captures an image ofsurface properties of a recording material and which determines a typeof the recording material or the like instead of performing colorimetryof a patch image.

Fourth Embodiment

In the first to third embodiments described above, detecting means fordetecting an open/closed state of the shutter 14 in the colorimetricunit 10 is separately provided for detecting whether the shutter 14 isopen or closed. In addition, realizing an operation of moving thecolorimetric unit 10 to the first position (the contact position) atwhich a recording material is pressed and the second position (theseparation position) at which the pressing is released additionallyrequires detecting means for detecting a position of the colorimetricunit 10.

However, separately providing such detecting means causes cost to riseaccordingly.

In consideration thereof, in the fourth embodiment, a detectingapparatus and an image forming apparatus will be described which arecapable of detecting whether the opening/closing member is open orclosed and detecting a position of an apparatus main body including alight emitting element and a light receiving element without having tonewly add detecting means for detecting whether the opening/closingmember is open or closed and detecting means for detecting a position ofthe apparatus main body.

In the present embodiment, since an image forming apparatus to which thepresent invention is applied, a colorimetric unit which constitutes acolorimetric apparatus provided in the image forming apparatus, and anactuating mechanism of the colorimetric unit are the same as those ofthe first embodiment, same or corresponding functions to the firstembodiment and elements sharing the same configuration as those of thefirst embodiment will be assigned same reference characters and adetailed description will be omitted.

The colorimetric unit 10, the cam gear 17, the shutter 14, the slide cam15, and the like which constitute a colorimetric apparatus 100 accordingto the present embodiment are, for the most part, the same as those ofthe first embodiment as described above. However, as is apparent from acomparison between FIGS. 5 to 7 which show operations of the shutter 14and the colorimetric unit 10 in the first embodiment and FIGS. 15 to 17which show operations of the shutter 14 and the colorimetric unit 10 inthe present embodiment, the present embodiment differs from the firstembodiment in that both the sensor 19 and the light shielding section 15h which shields the sensor 19 are not provided.

FIG. 18 collectively shows a relationship among a rotational phase ofthe cam gear 17, a position of the colorimetric unit 10, and the degreeof shutter opening according to the present embodiment. In FIG. 18, anabscissa indicates a phase of the cam gear 17 and an ordinate indicatesa position of the colorimetric unit 10 and the degree of shutteropening.

As shown in FIG. 18, in the present embodiment, phases of the cam gear17 when the colorimetric unit 10 is at the contact position and theseparation position respectively exist with widths in a similar mannerto the first embodiment. In addition, phases of the cam gear 17 in theshutter open state and the shutter closed state also respectively existwith widths. Accordingly, stop positions of the motor 20 which performsa contacting/separating operation of the colorimetric unit 10 and anopening/closing operation of the shutter 14 can be roughly set andcontrol can be simplified. In addition, in the present embodiment, a DCbrush motor is used as the motor 20 in a similar manner to the firstembodiment. Since DC brush motors are inexpensive but rotational speedscharacteristically vary according to load torque, the lighter the loadtorque, the faster the rotation, and the heavier the load torque, theslower the rotation.

FIG. 19 shows a relationship between a phase of the cam gear 17 and aload torque applied to the motor 20 according to the present embodiment.In a similar manner to the first embodiment, an abscissa indicates aphase of the cam gear 17 and an ordinate indicates a load torque of themotor 20.

As shown in FIG. 19, a manner in which a load torque varies differsbetween a transition of the colorimetric unit 10 from the separationposition to the contact position and a transition from the contactposition to the separation position. This means that more time isrequired by the cam gear 17 to rotate from 180 degrees to 360 degreesthan to rotate by 180 degrees from 0 degrees which is the state shown inFIG. 15A. In other words, a longer time is required for a transitionfrom the contact position to the separation position than a transitionfrom the separation position to the contact position.

In the actuating mechanism of the colorimetric unit 10 according to thepresent embodiment described above, a sensor or the like for detectingphases of the cam gear 17, the slide cam 15, the shutter 14, and thelike is not provided unlike in the first to third embodiments.

Hereinafter, means for detecting a contact position and a separationposition of the colorimetric unit 10 and opening and closing of theshutter 14 in the present embodiment will be described with reference toFIGS. 20 to 22.

FIG. 20 is diagram showing, on a time axis, a relationship between anoutput of the colorimeter 11, a degree of shutter opening, and aposition of the colorimetric unit 10. An abscissa indicates time t, andan ordinate indicates a position of the colorimetric unit 10, a degreeof opening of the shutter 14, and an output of the colorimeter 11.

FIG. 21 is a block diagram of control of the motor 20 according to thepresent fourth embodiment. FIG. 22 is a flow chart for determining acontact position or a separation position of the colorimetric unit 10according to the present embodiment.

Depending on a difference in a colorimetric object between when theshutter 14 is open and when the shutter 14 is closed, the colorimeter 11outputs the first output (a first value) when the shutter 14 is open andoutputs the second output (a second value) when the shutter 14 isclosed. In other words, in a state where the recording material isabsent, the colorimetric object when the shutter 14 is open is an imageof the white reference plate 30 that is a reference section provided onthe transport surface Da opposite the colorimeter 11. On the other hand,the colorimetric object when the shutter 14 is closed is an image of anopposing section which opposes the colorimeter 11 of the shutter 14.

The first output and the second output are stored in the main bodycontrol portion 55 in advance, and the colorimeter 11 is actuated whenopening or closing the shutter 14. In addition, a determination that theshutter 14 is open is made when the output of the colorimeter 11 is thefirst output, and a determination that the shutter 14 is closed is madewhen the output of the colorimeter 11 is the second output.Alternatively, a determination that the position of the colorimetricunit 10 is the contact position (the first position) is made when theoutput of the colorimeter 11 is the first output, and a determinationthat the position of the colorimetric unit 10 is the separation position(the second position) is made when the output of the colorimeter 11 isthe second output.

In the present embodiment, black is adopted as a color of the shutter14. As shown in FIG. 20, since the colorimetric window 11 a is closed bythe shutter 14 when the colorimetric unit 10 is in the separation state,an output V (the second output) of black which is the color of theshutter 14 is sent to the main body control portion 55 from thecolorimeter 11. On the other hand, when colorimetry is performed by thecolorimeter 11 when the colorimetric unit 10 is in the contact state or,in other words, in the shutter open state, since the colorimetric window11 a opposes the white reference plate 30, an output W (the firstoutput) of white is sent to the main body control portion 55 from thecolorimeter 11. In other words, different outputs are detected by thecolorimeter 11 between the shutter closed state and the shutter openstate.

Therefore, in the present embodiment, the difference in output obtainedby the colorimeter 11 between the shutter closed state and the shutteropen state forms a basis of detection of the shutter being open orclosed and the colorimetric unit 10 being in contact or separated.

However, simply determining that the shutter 14 is in the closed stateand the colorimetric unit 10 is at the separation position when theoutput is V and determining that the shutter 14 is in the open state andthe colorimetric unit 10 is at the contact position when the output is Wcreates the following problem.

That is, as shown in FIG. 20, since a degree of opening of the shutter14 and a position and a phase of the colorimetric unit 10 are notconsistent with each other, making a determination simply based onoutput due to the degree of opening of the shutter 14 entails a risk ofdetermining a contact state even in a section denoted by J in FIG. 18.In addition, depending on characteristics of the colorimeter 11, whenthe colorimetric window 11 a is opened by a certain amount, a sameoutput as that when the colorimetric window 11 a is fully open may bereturned. In other words, there is a risk that the shutter 14 may bedetermined to be fully open even if it is not.

Control of the main body control portion 55 when the colorimetric unit10 makes a transition from the separation position to the contactposition will now be described with reference to FIGS. 20 and 21.

First, the motor 20 rotates in accordance with a signal from the mainbody control portion 55.

At this point, since the colorimetric unit 10 is at the separationposition, the output V of black is detected as the output of thecolorimeter 11. As the motor 20 rotates, the shutter 14 makes atransition to an open state due to the mechanism described earlier.Shortly after the motor 20 starts driving, as shown in FIG. 20, theoutput W of white is detected as the output of the colorimeter 11. Onceta has elapsed after detecting the output W, the main body controlportion 55 determines that the colorimetric unit 10 is reached thecontact state and stops the rotation of the motor 20. Meanwhile, themotor 20 is rotated in a similar manner during a movement from thecontact position to the separation position, and once tb has elapsedafter detecting the output V, the main body control portion 55determines that the colorimetric unit 10 is reached the separation stateand stops the rotation of the motor 20. In the present fourthembodiment, the motor 20 is stopped based on an elapsed time from a timepoint where the output of the colorimeter 11 becomes W or V instead ofan elapsed time from the start of rotation of the motor. This isbecause, as described earlier, the rotational speed of the motor 20 isnot constant. Accordingly, a contact/separation state of thecolorimetric unit 10 and opening/closing of the shutter can be reliablydetected at low cost.

Control Flow Chart

FIG. 22 shows a control flow chart in the main body control portion 55according to the present embodiment.

When a contact instruction or a separation instruction is issued, themotor 20 starts driving (STEP 1), and colorimetric operations areconsecutively performed by the colorimeter 11 during the driving of themotor 20 (STEPS 2 and 3). The term “consecutive” as used herein refersto performing colorimetric operations by actuating the colorimeter 11 aplurality of times (receiving light a plurality of times) at a shortsampling period t0 which enables a variation in output of thecolorimeter 11 to be sufficiently detected during an opening/closingoperation of the shutter 14.

In addition, in the case of a contact instruction, the colorimetric unit10 is determined to be at the contact position in a part (a perioddenoted by A in FIG. 20) of a period in which the output of thecolorimeter 11 is W, but the colorimetric operation is repeated when theoutput is not W (STEP 4). On the other hand, in the case of a separationinstruction, the colorimetric unit 10 is determined to be at theseparation position in a part (a period denoted by B in FIG. 20) of aperiod in which the output of the colorimeter 11 is V, but thecolorimetric operation is repeated when the output is not V (STEP 4).

Furthermore, in the case of a contact instruction, once to has elapsedafter detecting the output W, a determination is made that thecolorimetric unit 10 has reached the contact state (STEP 5), and therotation of the motor 20 is stopped (STEP 6). On the other hand, in thecase of a separation instruction, once tb has elapsed after detectingthe output V, a determination is made that the colorimetric unit 10 hasreached the separation state (STEP 5), and the rotation of the motor 20is stopped (STEP 6). Accordingly, the colorimetric unit 10 can bepositioned at the contact position or the separation position.

Moreover, in the present embodiment, since the shutter open state existswhen the colorimetric unit 10 is at the contact position, the shutteropen state is not independently detected. When independently detectingthe shutter open and closed states, the shutter open state may bedetermined in a part (a period denoted by N in FIG. 20) of a period inwhich the output of the colorimeter 11 is W. In addition, the shutterclosed state may be determined in a part (a period denoted by O in FIG.20) of a period in which the output of the colorimeter 11 is V.

In addition, the motor 20 according to the present embodiment has acharacteristic in that rotational speed varies in accordance with a loadtorque as described earlier. The load torque varies in accordance withfriction between the contact region 13 a of the colorimeter base 13 andthe slide cam 15 shown in FIGS. 16A to 16F, biasing pressure of thebiasing member 18, the environment, and the like. In addition, theoutput of the motor 20 and the output of the colorimeter 11 also containmachine difference and environmental variability. Therefore, timerepresented by the abscissa and output represented by the ordinate inFIG. 20 vary according to circumstances. In consideration thereof, inthe present embodiment, an initialization operation is automaticallyperformed before actually performing a contacting/separating operation.

Initialization Operation

Hereinafter, the initialization operation will be described.

The motor 20 is rotated for a certain period of time when power of theimage forming apparatus is turned on or before a colorimetric operationis actually performed. This period of time is sufficiently longer than acycle shown in FIG. 20, and a contacting/separating operation of thecolorimetric unit 10 is performed at least once or, in other words, atleast for one cycle. The colorimetric operation (at a sampling period oft0) by the colorimeter 11 is consecutively performed during this period,and the main body control portion 55 stores cycles (t1, t2, t3, and t4)of contact/separation and output variations of the outputs V and W thatrepresent amplitudes as shown in FIG. 20 at the time point.

In other words, a time t1 during which the output is V, a transitiontime t2 from the output V to the output W, a time t3 during which theoutput is W, and a transition time t4 from the output W to the output Vare stored. Based on the stored information on the cycles, ta and tb aredetermined. For example, ta is set so that the cam gear 17 is reliablystopped during a period where the cam gear phase indicated by theabscissa in FIGS. 15A to 15F ranges from 120 degrees to 270 degrees suchas setting 10% of t3 as ta.

In a similar manner, tb is set so that the cam gear 17 is reliablystopped during a period where the cam gear phase indicated by theabscissa in FIGS. 15A to 15F ranges from 0 degrees to 90 degrees. Inaddition, when the main body control portion 55 stores the outputs W andV which are amplitudes, desirably, a value obtained by cutting a top fewpercent and a bottom few percent from an actual output amplitude is usedas a reference value and outputs exceeding the reference value arerespectively adopted as W and V. Accordingly, a colorimetric variationof the colorimeter 11 can be absorbed.

As described above, according to the present embodiment, using adifference between an output of the colorimetric unit 10 when theshutter 14 is open and an output of the colorimetric unit 10 when theshutter 14 is closed, an open/closed state of the shutter 14 can bedetermined and a contact/separation position of the colorimetric unit 10can be detected.

Therefore, contact/separation control of the colorimetric unit 10 can beperformed without newly adding means for opening/closing detection ofthe shutter 14 or means for contact/separation detection, and areduction in cost can be achieved.

Fifth Embodiment

Next, a fifth embodiment of the present invention will be described withreference to FIGS. 23A and 23B.

FIGS. 23A and 23B are enlarged sectional views of a colorimetricapparatus according to the present embodiment.

The fourth embodiment is configured such that the white reference plate30 is arranged on the colorimetric surface Z opposite the colorimetricunit 10. In contrast, in the present embodiment, the white referenceplate 30 is arranged on the back of a shutter 114, and an opposingportion of the colorimetric unit 10 is formed in a color which causes anoutput that differs from a white reference to be made. Since a driveconfiguration and control specifications of the colorimetric unit 10according to the present embodiment are the same as those of the fourthembodiment, same components will be denoted by same reference charactersand a description thereof will be omitted.

In the present embodiment, the white reference plate 30 is arranged onthe back of the shutter 114. In an aspect in which the shutter 14 ishoused inside the colorimetric unit 10 as in the fourth embodiment, adistance to the colorimeter 11 differs between performing colorimetry ofthe white reference plate 30 and performing colorimetry of the recordingmaterial P. Therefore, the present embodiment adopts a configuration inwhich the shutter 114 is provided outside the colorimetric unit 10, andwhen the colorimetric unit 10 moves to a contact/separation position,the entire colorimetric unit 10 moves forward or backward so as tostraddle the shutter 114.

In the present embodiment, an output of the colorimeter 11 in the caseof the white reference plate 30 is W and an output of the colorimeter 11is V when assuming that an opposing transport surface is black is V, andthe diagram of colorimeter output in FIG. 20 according to the fourthembodiment is reversed so that an output portion of W becomes V and anoutput portion of V becomes W. Therefore, a section of A in which theoutput is V may be determined as a contact state and a section of B inwhich the output is W may be determined as a separation state.

As described above, according to the present embodiment, even when thewhite reference plate 30 is arranged on the back of the shutter 114, adistance between the colorimetric surface Z and the white referenceplate 30 and a distance between the colorimetric surface Z and therecording material P can be made the same. Therefore, using a differencebetween an output of the colorimetric unit 10 when the shutter 114 isopen and an output of the colorimetric unit 10 when the shutter 114 isclosed, an open/closed state of the shutter 114 can be detected and acontact/separation position of the colorimetric unit 10 can be detected.

Therefore, contact/separation control of the colorimetric unit 10 can beperformed without newly adding means for opening/closing detection ofthe shutter or means for detecting contact/separation positions, and areduction in cost can be achieved.

Other Embodiments

Although configurations that differ in terms of positional relationshipsamong the colorimeter 11, the shutter (14 or 114), and the whitereference plate 30 have been described in the fourth and fifthembodiments, the present invention is not limited thereto and apositional relationship or a configuration which differs from theseexamples may be adopted.

For example, in the fourth and fifth embodiments, a position of thecolorimetric surface Z from the colorimeter 11 is more or less the samein the case of the white reference plate 30 and in the case of therecording material P. However, in a case where a focal length of thecolorimeter 11 is variable or a depth of focus has sufficient width, asshown in FIGS. 24A and 24B, a shutter 214 having the white referenceplate 30 may be arranged inside the colorimetric unit 10.

In this case, a configuration in which the recording material P issandwiched as in the first and second embodiments need not necessarilybe adopted. For example, a system in which the recording material P istransported along the colorimetric unit 10 as shown in FIG. 24A or asystem in which the recording material P is transported along theopposing transport surface Da of the duplex transport path D as shown inFIG. 24B are conceivable.

In other words, in the configuration shown in FIG. 24A, the colorimetricunit 10 is constituted by the colorimeter cover 12 as a cover memberwhich covers the colorimeter 11, and a distance between the recordingmaterial P and the colorimeter 11 is kept constant by bringing thecolorimeter cover 12 into contact with the recording material P. Inaddition, the shutter 214 provided with the white reference plate 30 isarranged inside the colorimeter cover 12, the colorimetric unit 10 isfixed without being moved forward or backward with respect to theopposing transport surface Da, and the recording material P istransported along a front surface of the colorimeter cover 12.

In addition, in the configuration shown in FIG. 24B, the colorimetricunit 10 is constituted by the colorimeter cover 12 as a cover memberwhich covers the colorimeter 11, and the shutter 214 provided with thewhite reference plate 30 is arranged inside the colorimeter cover 12.The colorimetric unit 10 is fixed without being moved forward orbackward with respect to the opposing transport surface Da, and therecording material P is separated from the colorimeter cover 12 andtransported along the opposing transport surface Da.

When adopting a system such as those shown in FIGS. 24A and 24B, acontacting/separating operation of the colorimetric unit 10 need nolonger be performed, and only detection of opening/closing of theshutter 214 may be performed using output of the colorimeter 11 bycontrol specifications as described in the fourth embodiment. Even inthis case, detection can be performed based on a difference in outputsof the colorimeter 11 between the shutter open state and the shutterclosed state.

In addition, while the white reference plate 30 is arranged as areference in the embodiments described above, a reference chart having areference color for each color may be adopted instead of the whitereference plate 30. Furthermore, the reference plate or the referencechart may be omitted as long as performance as a colorimetric unit canbe guaranteed. The present invention can be applied in configurations inwhich an output of a colorimetric apparatus differs between a shutteropen state and a shutter closed state.

Moreover, while a colorimetric unit that performs colorimetry of a colorpatch image has been described as an example of a colorimetric apparatusin the respective embodiments presented above, a colorimetric unit thatperforms colorimetry of a black and white patch image may be usedinstead. In addition, the detecting apparatus may be used in a so-calledmedia sensor that is an imaging apparatus which captures an image ofsurface properties of a recording material and which determines a typeof the recording material or the like instead of performing colorimetryof a patch image.

While the present invention has been described with reference toexemplary embodiments, it is to be understood that the invention is notlimited to the disclosed exemplary embodiments. The scope of thefollowing claims is to be accorded the broadest interpretation so as toencompass all such modifications and equivalent structures andfunctions.

This application claims the benefit of Japanese Patent Applications No.2017-173126, filed on Sep. 8, 2017, and No. 2017-173139, filed on Sep.8, 2017, which are hereby incorporated by reference herein in theirentirety.

What is claimed is:
 1. A detecting apparatus for detecting a patch imagebeing fixed on a sheet as a detection material, the detecting apparatuscomprising: a light emitting element that emits light toward thedetection material; a light receiving element that receives lightreflected from the detection material; and an opening/closing memberthat opens and closes an opening through which light emitted from thelight emitting element and light reflected from the detection materialpass through, wherein the detecting apparatus is capable of movingbetween a first position and a second position, with the detectingapparatus being more separated from the detection material when thedetecting apparatus is in the second position than when the detectingapparatus is in the first position, wherein the detecting apparatusdetects the detection material when in the first position and does notdetect the detection material when in the second position, and whereinthe opening/closing member opens when the detecting apparatus is in thefirst position and closes when the detecting apparatus is in the secondposition.
 2. The detecting apparatus according to claim 1, wherein thedetecting apparatus comes is in contact with the detection material whenin the first position and is separated from the detection material whenin the second position.
 3. The detecting apparatus according to claim 1,wherein the opening/closing member opens in accordance with a movementof the detecting apparatus to the first position and closes inaccordance with a movement of the apparatus main body to the secondposition.
 4. The detecting apparatus according to claim 1, furthercomprising: an opening/closing member drive portion that opens andcloses the opening/closing member; and an apparatus drive portion thatmoves the detecting apparatus, wherein the opening/closing member driveportion and the apparatus drive portion are driven by a single drivingsource.
 5. The detecting apparatus according to claim 1, furthercomprising: an opening/closing member drive portion that opens andcloses the opening/closing member; and an apparatus drive portion thatmoves the detecting apparatus, wherein the movement of the detectingapparatus and the opening/closing operation of the opening/closingmember are independent of each other, and wherein the opening/closingmember drive portion and the apparatus drive portion are driven bydifferent driving sources.
 6. The detecting apparatus according to claim4, wherein the apparatus drive portion includes: a biasing member thatbiases the detecting apparatus in a contact direction of the firstposition; and a cam mechanism that causes the detecting apparatus toreciprocate between the first position and the second position, wherein,when the detecting apparatus is in the first position, the detectingapparatus is pressed toward the detection material by the biasingmember, and wherein, when the detecting apparatus is in the secondposition, the detecting apparatus is held at the second position by thecam mechanism against a pressing force of the biasing member.
 7. Thedetecting apparatus according to claim 6, wherein the cam mechanism hasa slide cam that operates in a direction perpendicular to a direction ofoperation of the detecting apparatus, and wherein the cam mechanism hasa rotating cam which is rotationally driven by the driving source andwhich linearly drives the slide cam, and the cam mechanism having anidle period in which drive is not transmitted to the slide cam from therotating cam after the detecting apparatus arrives at the first positionor the second position.
 8. The detecting apparatus according to claim 7,wherein the rotating cam is given rotational drive only in one directionfrom the driving source.
 9. The detecting apparatus according to claim4, wherein the opening/closing member is biased in one of an openingdirection and a closing direction, and the opening/closing member driveportion performs driving only in an opposite direction to a biasingdirection of the opening/closing member.
 10. The detecting apparatusaccording to claim 9, wherein the opening/closing member is biased inthe opening direction by the opening/closing member's own weight, andwherein (i) the opening/closing member drive portion performs drivingonly in a direction in which the opening/closing member is closed or (i)the opening/closing member is biased by a biasing member that biases theopening/closing member.
 11. The detecting apparatus according to claim1, further comprising: a control portion that controls movement of thedetecting apparatus and opening/closing of the opening/closing member,wherein the light receiving element is configured to output a firstoutput when the opening/closing member is open and output a secondoutput, which differs from the first output, when the opening/closingmember is closed, and wherein the control portion determines that theopening/closing member is open when the first output is output anddetermines that the opening/closing member is closed when the secondoutput is output.
 12. The detecting apparatus according to claim 11,wherein the control portion receives light reflected from the detectionmaterial a plurality of times by the light receiving element during anopening/closing operation of the opening/closing member, determines thatthe opening/closing member is open in a period of a prescribed portionof a period during which the light receiving element outputs the firstoutput, and determines that the opening/closing member is closed in aperiod of a prescribed portion of a period during which the lightreceiving element outputs the second output.
 13. The detecting apparatusaccording to claim 1, wherein the detection material is transportedalong a transport path inside an image forming apparatus, and whereinthe detecting apparatus comes into contact with the detection materialbeing transported in the transport path when the detecting apparatus isin the first position.
 14. The detecting apparatus according to claim 1,wherein the detection material is transported along a transport pathinside an image forming apparatus, and wherein the detecting apparatusis separated from the detection material being transported in thetransport path when the detecting apparatus is in the second position,and the detection material is transported along a transport surfaceopposite thereto.
 15. The detecting apparatus according to claim 11,wherein the opening/closing member opens in accordance with a movementof the detecting apparatus to the first position and closes inaccordance with a movement of the apparatus main body to the secondposition, and wherein the control portion determines that the detectingapparatus is in the first position when the first output is output anddetermines that the detecting apparatus is in the second position whenthe second output is output.
 16. The detecting apparatus according toclaim 15, wherein the control portion receives light reflected from thedetection material a plurality of times by the light receiving elementduring an opening/closing operation of the opening/closing member,determines that the detecting apparatus is in the first position in aperiod of a prescribed portion of a period during which the lightreceiving element outputs the first output, and determines that thedetecting apparatus is in the second position in a period of aprescribed portion of a period during which the light receiving elementoutputs the second output.
 17. The detecting apparatus according toclaim 11, wherein before detecting the detection material, the controlportion performs an opening/closing operation of the opening/closingmember at least once, and stores a cycle of output variation of thelight receiving element.
 18. The detecting apparatus according to claim1, wherein the detecting apparatus is provided with a dispersing unitfor dispersing light reflected from the detection material and the lightreceiving element receives the dispersed light from the dispersing unit.19. The detecting apparatus according to claim 18, wherein a referencesection used as a reference when performing colorimetry of the patchimage is provided before performing colorimetry of the patch image, andwherein the reference section outputs the first output in a portiondetected by the light receiving element when the opening/closing memberis open or the reference section outputs the second output in a portiondetected by the light receiving element when the opening/closing memberis closed.
 20. The detecting apparatus according to claim 1, wherein thelight receiving element is a sensor which images surface properties ofthe detection material and which is used as an imaging apparatus fordetermining a type of the detection material.
 21. An image formingapparatus comprising: an image forming unit forming an image on a sheet,and the detecting apparatus according to claim 1, wherein a condition ofan image formation of the image forming unit is controlled according toa detection result of the detecting apparatus.